How to get a variable from Apache configuration inside a module?

Question

I am creating my own Apache module. How to get a variable from Apache configuration inside a module?

See the variable "some_var_config_from_apache_or_htaacess" inside the Apache module:

/* Source: http://people.apache.org/~humbedooh/mods/examples/mod_example_1.c */

/* Include the required headers from httpd */
#include "httpd.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_request.h"

static void register_hooks(apr_pool_t *pool);
static int example_handler(request_rec *r);

/* Define our module as an entity and assign a function for registering hooks  */

module AP_MODULE_DECLARE_DATA   example_module =
{
    STANDARD20_MODULE_STUFF,
    NULL,            // Per-directory configuration handler
    NULL,            // Merge handler for per-directory configurations
    NULL,            // Per-server configuration handler
    NULL,            // Merge handler for per-server configurations
    NULL,            // Any directives we may have for httpd
    register_hooks   // Our hook registering function
};

static void register_hooks(apr_pool_t *pool) 
{
    ap_hook_handler(example_handler, NULL, NULL, APR_HOOK_LAST);
}

/* The handler function for our module.
 * This is where all the fun happens!
 */

static int example_handler(request_rec *r)
{
    if (!r->handler || strcmp(r->handler, "example-handler")) return (DECLINED);

   // The first thing we will do is write a simple "Hello, world!" back to the client.
   //ap_rputs("Hello, world!", r);
   ap_rputs(some_var_config_from_apache_or_htaacess, r);

   return OK;
}